6 tbsp. butter
1/3 c. granulated sugar
1 to 2 egg yolks
1/4 tsp. finely grated lemon zest
1 c. all-purpose flour

With an electric mixer, beat butter and sugar until light. Beat in egg yolk (2 yolks will make a slightly richer cookie) and lemon zest. Stir in flour with a spoon or rubber spatula. Refrigerate dough.

Roll chilled dough into 1-inch balls. Place balls on greased baking sheet. Slightly flatten each ball with your thumb or the bottom of a glass. Bake in preheated 375 degree oven 10 to 12 minutes, or until edges brown. Let cool on a rack. Makes 24 to 30 cookies.